1. Field of the Invention
This invention relates to electromagnetic relays.
2. Description of Related Art
Although there have been many recent advances in the technology related to all-electronic switching devices, electromagnetic relays are still required in many applications for which all electronic devices are not suitable. As a result, there is a need for reliable electromagnetic relays, particularly in applications where the device is subject to vibration, high impact, high acceleration, and fluctuating thermal and humidity conditions.
In the past, electromagnetic relays which were capable of withstanding these adverse conditions, have often been internally complex. As a result, many such prior art devices are expensive and difficult to manufacture. For example, a typical prior art relay is a model 412K Series TO-5 Relay manufactured by the Teledyne Corporation. This relay includes a clipper type armature having two small push pins with an insulating glass bead to push a contact reed from a first position to a second position when the electromagnetic force attracts the armature, and a return spring to push the armature to its first position when the electromagnet is deactivated. The construction of the armature as well as the complex arrangement of its contact members makes this relay extremely difficult to manufacture. This design also has a relatively high number of moving parts and welded joints which are subject to failure. As a result, the reliability of this relay limits its usefulness in many applications.
Another previous design replaces the spring and armature system with a bar-shaped slider which is mechanically coupled to the contact reed. The slider is provided with a permanent magnet which is normally attracted to the electromagnet; thus, holding the slider and the contact reed in a first position. Activation of the electromagnet repels the permanent magnet moving the slider and the reed to a second position. However, because of present technological limitations, this design is not suitable for miniaturization to a standard TO-5 case relay.